Apparatus for detecting fogged window of vehicle

ABSTRACT

A fog sensing apparatus for vehicle windows is provided. The fog sensing apparatus includes: a temperature/humidity sensor module including a glass surface temperature sensor for measuring a temperature of a glass surface of the vehicle window, and a humidity sensor for measuring relative humidity around the glass surface of the vehicle window; a flexible printed circuit board on which the temperature/humidity sensor module is mounted, which a temperature measurement part of the glass surface temperature sensor contacts, and on which a conductive pattern is formed to be connected to electrode terminals of the glass surface temperature sensor and electrode terminals of the humidity sensor; a substrate assembly having a through hole for the temperature/humidity sensor module to pass through, and connection terminals connected to the conductive pattern; and a case covering the substrate assembly, the substrate assembly interposed between the case and the flexible printed circuit board.

TECHNICAL FIELD

The present invention relates to a fog sensing apparatus for vehiclewindows, and more particularly, to a fog sensing apparatus for vehiclewindows which can effectively prevent fog from forming on a vehiclewindow by correctly measuring a temperature of the glass surface of thevehicle window.

BACKGROUND ART

In general, a vehicle is equipped with a sensor for preventing fog fromforming on the vehicle's window. The sensor is connected to an airconditioning system of the vehicle to automatically remove fog formed onthe vehicle's window, thereby supporting safe driving.

Various apparatuses for preventing fog from forming on a vehicle windowhave been developed both at home and abroad. An example of suchapparatuses is disclosed in U.S. Pat. No. 6,422,062 entitled “anintegrated glass fog sensor unit” by Delphi Corp. In the conventionaltechnique, the integrated glass fog sensor unit includes a glass surfacetemperature sensor, an ambient air temperature sensor, and a relativehumidity sensor, and measures humidity and a temperature at the samelocation by locating the relative humidity sensor adjacent to theambient air temperature sensor to obtain an exact dew point temperature.

DISCLOSURE OF INVENTION Technical Problem

However, in the conventional technique, since the temperature measuringpart of the glass surface temperature sensor is attached to a glasssurface via an adhesive layer to measure a temperature of the glasssurface, a gap may be formed between the temperature measuring part andthe adhesive layer when the adhesive layer is attached to a curved glasssurface, when foreign materials are collected between the temperaturemeasuring part and the adhesive layer, etc., which may make the glasssurface temperature sensor to measure a wrong temperature value and thusmay cause fog to form on the glass surface.

Technical Solution

The present invention provides a compact fog sensing apparatus whicheffectively prevents fog from forming on a glass surface by correctlymeasuring a temperature of the glass surface.

Advantageous Effects

As described above, the fog sensing apparatus according to the presentinvention can prevent fog from forming on a vehicle window in connectionwith an air conditioning system of a vehicle by correctly measuring atemperature of the glass surface of the vehicle window to obtain anexact dew point temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fog sensing apparatus for vehiclewindows according to an embodiment of the present invention;

FIG. 2 is an exploded perspective view of the fog sensing apparatusillustrated in FIG. 1;

FIG. 3 is a wiring diagram of a flexible printed circuit board (FPCB)included in the fog sensing apparatus illustrated in FIG. 2; and

FIG. 4 is a cross-sectional view of the fog sensing apparatusillustrated in FIG. 1 which is attached to a glass surface of a vehiclewindow.

BEST MODE FOR CARRYING OUT THE INVENTION

According to an aspect of the present invention, there is provided a fogsensing apparatus for a vehicle window, including: atemperature/humidity sensor module including a glass surface temperaturesensor for measuring a temperature of a glass surface of the vehiclewindow, and a humidity sensor for measuring relative humidity around theglass surface of the vehicle window; a flexible printed circuit board onwhich the temperature/humidity sensor module is mounted, which atemperature measurement part of the glass surface temperature sensorcontacts, and on which a conductive pattern is formed to be connected toelectrode terminals of the glass surface temperature sensor andelectrode terminals of the humidity sensor; a substrate assembly havinga through hole for the temperature/humidity sensor module to passthrough, and connection terminals connected to the conductive pattern;and a case covering the substrate assembly, the substrate assemblyinterposed between the case and the flexible printed circuit board.

MODE FOR THE INVENTION

FIG. 1 is a perspective view of a fog sensing apparatus for vehiclewindows according to an embodiment of the present invention, and FIG. 2is an exploded perspective view of the fog sensing apparatus illustratedin FIG. 1.

Referring to FIGS. 1 and 2, the fog sensing apparatus 100 for vehiclewindows includes a temperature/humidity sensor module 110, a flexibleprinted circuit board (FPCB) 120, a substrate assembly 130, and a case140.

The temperature/humidity sensor module 110 includes a glass surfacetemperature sensor for measuring a temperature of the glass surface 10(see FIG. 4) of a vehicle window, and a humidity sensor for measuringrelative humidity around the glass surface 10. The glass surfacetemperature sensor may be a thermistor, or any other well-knowntemperature sensor. A temperature measurement part of the glass surfacetemperature sensor is exposed, and two electrode terminals are drawn outfrom the glass surface temperature sensor. Here, the temperaturemeasurement part may be a part of the electrode terminals. Also, thehumidity sensor may be a capacitive humidity sensor. If the humiditysensor is a capacitive humidity sensor, the humidity sensor includes twoelectrodes and a hygroscopic high molecular thin film therebetween.Likewise, electrode terminals are drawn out from the humidity sensor.

Meanwhile, the temperature/humidity sensor module 110 may be a MicroElectro Mechanical Systems (MEMS) type sensor using a MEMS technology sothat it can be miniaturized. As the temperature/humidity sensor module110 is miniaturized, a glass surface area which the temperature/humiditysensor module 110 contacts is less influenced by the curve of the glasssurface. A filter 111 can be installed in an air inflow channel formedin the humidity sensor of the temperature/humidity sensor module 110.The filter 111 removes foreign materials from air supplied through anair inflow hole 142 of the case 140, and supplies only humidity to thehumidity sensor. The filter 111 may be a membrane filter. The membranefilter may be made of a material such as Polytetrafluoroethylene (PTFE)Teflon or a nonwoven fabric.

The temperature/humidity sensor module 110 is mounted on the flexibleprinted circuit board 120. The flexible printed circuit board 120contacts the temperature measurement part of the glass surfacetemperature sensor so that heat from the flexible printed circuit board120 can be directly transferred to the temperature measurement part ofthe glass surface temperature sensor. That is, since heat is transferredthrough the flexible printed circuit board 120 with a relatively largearea from the glass surface 10 to the temperature measurement part ofthe glass surface temperature sensor, and the flexible printed circuitboard 120 can be attached to an adhesive layer 150 (which will bedescribed later) while being curved along the curve of the glass surface10, heat from the glass surface 10 can be transferred to the temperaturemeasurement part of the glass surface temperature sensor without heatloss. Therefore, it is possible to correctly measure a temperature ofthe glass surface 10 and effectively prevent fog from forming on theglass surface 10.

In order to transfer heat from the flexible printed circuit board 120 tothe temperature measurement part without heat loss, the flexible printedcircuit board 120 can further include a conductive part 124 made of aconductive material in a portion where the flexible printed circuitboard 120 contacts the temperature measurement part, as illustrated inFIG. 3. Since heat transfer of the glass surface 10 deteriorates and atemperature measurement error increases if the flexible printed circuitboard 120 is too thick, it is preferable that the flexible printedcircuit board 120 has a thickness less than 0.1 mm.

The flexible printed circuit substrate 120 includes a conductive pattern122 for connecting the respective electrode terminals of the glasssurface temperature sensor and humidity sensor to connection terminals134 of the substrate assembly 130. Here, the conductive pattern 122 maybe a copper foil pattern. As illustrated in FIG. 3, the conductivepattern 122 is formed on a base board 121, and includes lead terminals123 which are formed on the edge portions of the base board 121 in amanner to be exposed in correspondence to the connection terminals 134of the substrate assembly 130.

The substrate assembly 130 includes a through hole 131 through which thetemperature/humidity sensor module 110 passes. The connection terminals134 are connected to the conductive pattern 122 of the flexible printedcircuit board 120, that is, to the lead terminals 123 of the flexibleprinted circuit board 120, by soldering, etc., while thetemperature/humidity sensor module 110 is inserted into the through hole131. Bonding between the connection terminals 134 and the lead terminals123 may be weak if only soldering is made therebetween. In order tostrengthen the bonding between the connection terminals 134 and the leadterminals 123, by forming a plurality of holes in a portion of theflexible printed circuit board 120 where the substrate assembly 130contacts, filling the holes with epoxy, and hardening the epoxy, theflexible printed circuit board 120 is more tightly coupled with thesubstrate assembly 130.

Since the temperature/humidity sensor module 110 is inserted into thethrough hole 131 of the substrate assembly 130, and coupled with thesubstrate assembly 130 through the flexible printed circuit board 120,the fog sensing apparatus 100 can be easily attached on the glasssurface 10 of the vehicle window, while having a compact structure.

Also, the substrate assembly 130 includes substrate terminals 135 whichare connected to connector terminals 144 (which will be described later)of the case 140 by soldering, etc.

Meanwhile, in order to obtain an exact dew point temperature, an insidetemperature sensor 132 for measuring the inside temperature of a vehiclecan be provided. Also, the substrate assembly 130 further includes acontrol circuit module 133.

The control circuit module 133 compares a dew point temperature obtainedfrom values measured by the humidity sensor and the inside temperaturesensor 132, with a glass surface temperature measured by the glasssurface temperature sensor of the temperature/humidity sensor module110, and outputs a fog detection signal according to the result of thecomparison.

That is, the control circuit module 133 obtains the dew pointtemperature according to a well-known equation for calculating a dewpoint temperature from a relative humidity value and an insidetemperature value. Then, the control circuit module 133 compares the dewpoint temperature with the glass surface temperature, determines thatfog is formed on the glass surface 10 of the vehicle window if the dewpoint temperature is higher than the glass surface temperature, andoutputs a fog detection signal. The fog detection signal is provided tothe air conditioning system of the vehicle to prevent fog from formingon the glass surface 10 of the vehicle window.

The case 140 covers the substrate assembly 130 to protect the substrateassembly 130 when the flexible printed circuit board 120 and thesubstrate assembly 130 are attached to the glass surface 10 of thevehicle window, which will be described later. The case 140 has aconcave portion 141 into which the substrate assembly 130 is inserted.The case 140 is mechanically coupled with and fixed on the substrateassembly 130, or is attached to and fixed on the substrate assembly 130by an adhesive layer, etc.

An air inflow channel 142 is formed at a location of the case 140 whichcorresponds to the temperature/humidity sensor module 110. The airinflow channel 142 enables air to flow into the temperature/humiditysensor module 110 and into the humidity sensor of thetemperature/humidity sensor module 11 along the glass surface 10 of thevehicle window. A plurality of air inflow channels 142 may be formed ina lattice form in the corresponding location of the case 140.

A connector 143 for supplying power to the control circuit module 133and receiving/outputting data from/to the control circuit module 133 isprovided in a side of the case 140. The connector 143 is connected tothe control circuit module 133 through connector terminals. Thesubstrate assembly 130 includes substrate terminals 135 which are drawnout from the control circuit module 133 and connected to the connectorterminals 144 by soldering, etc. Meanwhile, in the case 140, a hole isformed toward the connector terminals 144 to facilitate soldering of theconnector terminals 144 and the substrate terminals 135, and the hole iscovered by a cover member 146 or with a molding material aftersoldering.

The connector 143 can be connected to a control box for controllingelectrical apparatus components of a vehicle, through a wire harness.Therefore, if the control box receives a fog detection signal from thecontrol circuit module 133 through the connector 143, the control boxperforms dehumidification using the air conditioning system to preventfog from forming on the glass surface 10 of the vehicle window.

In the case 143, pressure projections 145 are formed in a locationcorresponding to the temperature/humidity sensor module 110. Thepressure projections 145 are protruded toward the temperature/humiditysensor module 110. As illustrated in FIG. 4, the pressure projections145 apply pressure to the temperature/humidity sensor module 110 towardthe vehicle window when the fog sensing apparatus 100 is attached to thevehicle window via the adhesive layer 150, thereby causing the flexibleprinted circuit board 120 to be adhered closely to the adhesive layer150 and simultaneously causing the adhesive layer 150 to be adheredclosely to the vehicle window. Therefore, a temperature of the glasssurface 10 of the vehicle window can be more accurately measured.

The fog sensing apparatus 100 is attached to and fixed on the vehiclewindow by the adhesive layer 150. The adhesive layer 150 may extend overthe whole area of the substrate assembly 130 so that the adhesive layer150 can be adhered closely to the glass surface 10 of the vehiclewindow. Also, it is preferable that the adhesive layer 150 has thermalconductivity as well as adhesive property in order to facilitate heattransfer from the glass surface 10 of the vehicle window to the glasssurface temperature sensor of the temperature/humidity sensor module110. Also, it is preferable that the adhesive layer 150 is made of asoft material so that the adhesive layer 150 has sufficient adhesiveproperty when the adhesive layer 150 is adhered to a curved glasssurface.

INDUSTRIAL APPLICABILITY

The present invention can be applied to an apparatus for preventing fogfrom forming on the glass surface of a vehicle window.

The invention claimed is:
 1. A fog sensing apparatus for a vehiclewindow, comprising: an adhesive layer having a top adhesive surface anda bottom adhesive surface, the bottom adhesive surface being capable ofadhering to a glass surface of the vehicle window; a flexible printedcircuit board attached directly on the top adhesive surface of theadhesive layer, the flexible printed circuit having a conductivepattern; a temperature and humidity sensor module mounted directly onthe conductive pattern of the flexible printed circuit board, thetemperature and humidity sensor module including a glass surfacetemperature sensor for measuring a temperature of the glass surface ofthe vehicle window, and a humidity sensor for measuring relativehumidity around the glass surface of the vehicle window; a substrateassembly having a through hole for the temperature and humidity sensormodule to pass through, and connection terminals connected to theconductive pattern; and a case covering the substrate assembly, thesubstrate assembly interposed between the case and the flexible printedcircuit board, wherein the adhesive layer has heat conductivity tofacilitate heat transfer from the glass surface of the vehicle window tothe glass surface temperature sensor of the temperature and humiditysensor module.
 2. The fog sensing apparatus of claim 1, wherein thesubstrate assembly further comprises an inside temperature sensor formeasuring an inside temperature of the vehicle.
 3. The fog sensingapparatus of claim 2, wherein the substrate assembly further comprises acontrol circuit module comparing a dew point temperature obtained from avalue measured by the humidity sensor and a value measured by the insidetemperature sensor, with a glass surface temperature measured by theglass surface temperature sensor, and outputting a fog detection signalaccording to the result of the comparison.
 4. The fog sensing apparatusof claim 3, wherein the case further comprises a connector coupled withthe control circuit module to supply power to the control circuit moduleand receive data from the control circuit module or output data to thecontrol circuit module.
 5. The fog sensing apparatus of claim 1, whereinthe flexible printed circuit board has a thickness less than 0.1 mm. 6.The fog sensing apparatus of claim 1, wherein the case further comprisesa pressure projection formed at a location corresponding to thetemperature and humidity sensor module to apply pressure to thetemperature/humidity sensor module toward the glass surface of thevehicle window.
 7. The fog sensing apparatus of claim 1, wherein afilter for removing foreign materials from air supplied through an airinflow hole of the case is installed in an air inflow channel of thehumidity sensor of the temperature and humidity sensor module.
 8. Thefog sensing apparatus of claim 1, wherein the temperature and humiditysensor module is of a Micro Electro Mechanical Systems (MEMS) type.